diff --git a/src/adapter.github.js b/src/adapter.github.js
index 4e254153..f0c3bc20 100644
--- a/src/adapter.github.js
+++ b/src/adapter.github.js
@@ -13,26 +13,7 @@ const
   , GH_PJAX_SEL         = '#js-repo-pjax-container'
   , GH_CONTAINERS       = 'body > .container, .header > .container, .site > .container, .repohead > .container'
 
-function GitHub() {
-  // Fix #151 by detecting when page layout is updated.
-  // In this case, split-diff page has a wider layout, so need to recompute margin.
-  // In addition, can't do this in response to URL change, since new DOM might not be ready.
-  var observer = new MutationObserver(function(mutations) {
-    for (var i = 0, len = mutations.length; i < len; i++) {
-      var mutation = mutations[i]
-      if (~mutation.oldValue.indexOf('split-diff') ||
-          ~mutation.target.className.indexOf('split-diff')) {
-        return $(document).trigger(EVENT.LAYOUT_CHANGE)
-      }
-    }
-  })
-
-  observer.observe(document.body, {
-    attributes: true,
-    attributeFilter: ['class'],
-    attributeOldValue: true
-  })
-}
+function GitHub() {}
 
 /**
  * Selects a submodule.
@@ -63,28 +44,9 @@ GitHub.prototype.selectPath = function(path, tabSize) {
  */
 GitHub.prototype.updateLayout = function(sidebarVisible, sidebarWidth) {
   var $containers = $(GH_CONTAINERS)
-    , isSplitView = $(document.body).hasClass('split-diff')
-    , spacing = 10
-    , autoMarginLeft
-    , shouldPushLeft
-
-  if ($containers.length === 4) {
-    autoMarginLeft = ($('body').width() - $containers.width()) / 2
-
-    if (isSplitView) {
-      $containers.css('margin-left', 'auto')
-      if (sidebarVisible) $containers.css('padding-left', sidebarWidth + spacing)
-      else $containers.css('padding-left', 30)
-    }
-    else {
-      $containers.css('padding-left', 0)
-      if (sidebarVisible) $containers.css('margin-left', sidebarWidth + spacing)
-      else $containers.css('margin-left', 'auto')
-    }
-  }
-
-  // falls-back if GitHub DOM has been updated
-  else $('html').css('margin-left', sidebarVisible ? sidebarWidth - spacing : 0)
+  $containers = $containers.length === 4 ? $containers : $('html') // falls-back if GH DOM is changed
+  if (sidebarVisible) $containers.css('margin-left', sidebarWidth + 10)
+  else $containers.css('margin-left', 'auto')
 }
 
 /**
diff --git a/src/constants.js b/src/constants.js
index 28ee744b..92c3af55 100644
--- a/src/constants.js
+++ b/src/constants.js
@@ -37,7 +37,6 @@ const
   , EVENT = {
     TOGGLE        : 'octotree:toggle',
     LOC_CHANGE    : 'octotree:location',
-    LAYOUT_CHANGE : 'octotree:layout',
     REQ_START     : 'octotree:start',
     REQ_END       : 'octotree:end',
     OPTS_CHANGE   : 'octotree:change',
diff --git a/src/octotree.js b/src/octotree.js
index 4c9c2280..9681b42e 100755
--- a/src/octotree.js
+++ b/src/octotree.js
@@ -63,7 +63,6 @@ $(document).ready(function() {
         event.preventDefault()
       })
       .on(EVENT.LOC_CHANGE, tryLoadRepo)
-      .on(EVENT.LAYOUT_CHANGE, layoutChanged)
       .on(EVENT.TOGGLE, layoutChanged)
 
     return tryLoadRepo()